Import a VFC with a property like:

      int_with_greaterThanEqual5:
        type: integer
        required: false
        constraints:
        - greater_or_equal: 5
 

Export the VFC. In the geneated tosca, the constraint value is represented as a string but should be an integer value:

      int_with_greaterThanEqual5:
        type: integer
        required: false
        constraints:
        - greater_or_equal: '5'
 

Not the value type will not always be numeric, it depends on the type of the property. It should be an integer in this example because the property is an integer. It is the same problem for other types (e.g. float). If the property was a string then the behaviour is ok. 

The same behaviour is seen for other constraints where the type of the value is dependent on the type of the property